Hot-blast stove



W. O. AMSLER.

HOT BLAST STGVE.

APPLICATION FILED FEB. 19. 1912.

l ,3 1 9,985 o Patented Oct. 28, 1919.]

2 SHEETQ-SHEET 1.

35 WITNESSES W. O. AMSLER.

HOT BLAST 'SIOVE.

APPLICATION FILED FEB. L9, 1917.

Patented Oct. 28, 1919.

2 SHEETSSHEET 2- FIG.Z

FIELB.

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WALTER'O. AMsLEaoF nnenwoon, rEnNsYLvANIA.

HOT-BLAST srovn. r

Specification bf Letters Patent.

Patented'Oct. as, 1 919.

Application-filed February 19, 1917. Serial No. 149,450..

To all whom it may concern:

Be it known that I, WALTER O. AMsLnR, a citizen of the United States, residing at Edgewood, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Hot Blast Stoves,-of which the following is. a. specification. r

My invention relates to improvements in hot blast stoves. Hot blast stoves as here tofore constructed have generally been either of thetw0 pass or the three pass type. Each of these types of stoves have certain advantages one over the other and certain disadvantages. Thus, the two-pass stove with all its valves on the ground level and its simple interior construction is very well adapted for certain small constructions. It is often built with a side combustion chain ber for the reason that the central combustion type presents a large annular space for 1 thesecond and downward pass for the prod= nets of combustion, which it is very'difiicult to fill with a. satisfactory radial and. circumferential tile. The central combustion chamber type, however, affords a much better' opportunity for taking-care of the eX- pansion and contraction of the masonry, which it is almost impossible to do withthe. side combustion chamber and square fine checker-work; It is not practicable to reduce the diameter of the stove and to increase the height in order to make amore practical radial checker brick construction,

since the stress in the brick work at the botwhich is anideal arrangement in that it has 7 the hottest part of the stovein the-center and reduces radiation losses, the .three pass stove was introduced. Certain disad vantages of the three pass stove'are, first, that the chimney valve and the cold blast I valve are at the top of the stove where they are difficult to inspect and repair, and, second, that in such type ofconstruction, the products of combustion are caused to ascend throughthe checker-work and the cold air to descend, which action produces a conch tion of unstable temperature equilibrium,

for if any part of the third pass becomes slightly cold, as for instance by the impact. of the wind directed against such part, the ascending hot gas 'Willavoid this part of the checker-work and the descending cold air will favor it and aggravate the trouble.

The present invention is embodied in the four pass type of stove, and the construetionis designed to in'cludethe advantages found'in both the. two pass and the three pass stoves without the respective disad-l vantages thereof above enumerated.

f-Thus, the present invention has all the advantages of the two pass construction in i that it has all the valves on the ground level without the disadvantages of uneven expansion and disintegration of the masonry, and

it also possesses the advantages of the .three pass stove central combustion chamber withoutthe disadvantages of the third pass.-

- My improved-stove provides a construction which permits a practicable radial checker work which will permit independent expansion for. each .pass. It also provides for the descent of the hotgas through all the checker-work and the ascent of the cold air,

which will automatically insure a uniform temperature of gradient throughout the checker-work- This stove will" also permit oflarger diameters, and consequently of. stoves of'larger capacity for; the same height, which height as heretofore stated must be confined to certain limits on account of the crushing strength of the brick. The invention is embodied in preferable form in: the construction hereinafter described and illustrated in the accompanying drawings. I

.In these drawings, 1 Figure 1 is a central vertical section of a stove embodying my invention. --Fig. 2 is a horizontal section on the, lin 2 -2 of Fig; 1-. v Fig; 3 is a horizontal section on the line 3-3 or Fig.1.

.The stove comprisesan outer steel'shell entirely inclosing the stove and having a dome 2 within which is mounted the brick crown 3-. This shell is provided with upper cleaning doors .4 at the top of the structure and with lower cleaning doors 5 at the bottom thereof, and these doors are preferably made of flanged cast iron. In the interior of the shell the stove is formed with fire brick masonry walls 6, 7 and 8 of annular cylindrical form and radially spaced one from another successively, thereby providing four passageways, namely, the central combustion chamber 9 which constitutes the first pass, an annular passageway or chamber 10 which constitutes the second pass, a passage 11 provided by a series of fiues formed in the wall 7 and constituting the third pass, and an annular passageway or chamber 12 between the walls 7 and 8 and constituting the fourth pass. It will be noted that the third pass 11 is formed directly in the wall 7 by means of a series of small separated tlues 13. The combined area of these separate fiues is preferably equal to the cross sectional area of the chimney flue 14. The main purpose of this pass is to transfer the gas and products of combustion from the bottom of the second pass to thetop of the fourth passas quickly as possible and without attempting regeneration; consequently, the area mentioned is the most desirable. If the combined area of the said fines were smaller it would offer too much resistance, and if larger it would create an uneven draft liable to cause a back draft.

Located within the passageways 10 and 12 which constitute the second and fourth.

passes, I provide checker-work indicated respectively at 15 and 16. It will be noted that there is considerably more checker.- work in the outer pass 12 than in the inner pass 10, and the purpose of this is to pro.- vide a greater fiue space in the checkerwork in the pass 10 to permit some accumulation of dust without interfering with the operation of the stove, It will be understood, of course, that in this pass there is considerably more dust carried in the gas than when the gas reaches the outer pass 12. 17 designates a filling of kieselguhr interposed between the outside surface of the outer masonry wall and the metallic shell.

The top of the wall 7 forming the third pass 11 makes a slip' joint with the crown 3, whereby the entire third pass wall may expand and contract without disturbing the masonry of either the second pass 10 or the fourth pass 12 or the crown 3. This joint is formed by a projection 18 formed on independent blocks 19 and the projection depends from the crown and provides a cylindrical inner surface to engagewith the cylindrical outer surface of the passwall 7. This depending cylindrical surface is 'constructed with special tile which may be )uilt into the crown 3 and the blocks 19 .re preferably independent of the construcion of the crown and inserted therein.

Leading into the central combustion chamber near the bottom of the stove is an air intake conduit 20 which is controlled by a valve 21. Also communicating with the combustion chamber at substantially the same level as the air inlet is a gas intake conduit 22 provided with a door 23. Lead ing from the central combustion chamber preferably by way of the gas conduit is a hot blast outlet conduit 24 which is controlled by valve 25.

The successive passes are adapted to communicate alternately at the top and bottom, and to this end, there is provided a space 26 at the top of the stove under the dome thereof communicating with the central combustion chamber 9, and at the bottom of the stove an annular chamber or connecting line 27 communicating with the second pass 10, and surrounding this chamber is another annular chamber or connecting flue 28 which communicates with the bottom of the fourth or outer pass 12. An annular space 29 at the top of the stove communicates with the upper ends of the checkerwork of the third pass. The last annular chamber 28 communicates with a connecting conduit 30 leadingto the chimney flue let, which chimney flue is controlled by valve. 31. Leading into the flue 30 is a cold blast inlet 32 controlled by a valve33.

Located under the combustion chamber, below the level of the passageways 20 and 22 is aslag pocket 34, having a passage 35 adapted to be closed by the cleaning door By the provision of this slag pocket 34., it will be understood that the dust, etc., will accumulate therein instead of in the central combustion chamber 9 at the inner ends of the passageways 20 and 22, as heretofore in constructions of this character. By means of this slag pocket and the ready accessibility thereto through the opening 35, it is possible to readily remove all slag, etc, from the stove in a much more convenient manner than has been possible heretofore. This pocket is a characteristic feature of the invention and is not limited in its application to a four pass stove.

The operation of the stove is as follows: The cold blast valve 33 and the hot blast valve 25 being first closed and the chimney valve 31 being opened, the air valve 21 and gas valve 23 are then also opened and gas is introduced into the passageway 22 where it mixes with the air coming through passage 20 to form a combustible mixture which is burned in the central combustion chamber 9. The products of combustion then pass outer pass 12. They then pass downward through the checker-work in said outer pass 12 to the annular chamber 28 at the bottom- After the fire has been maintainedfora sufficient length of time to preheat the masonry, to the desired temperature, the gas conduit door 23 is closed, thereby shutting off the gas to the stove, the air valve 21 is closed, and also the chimney valve-31. F or convenience of operation, and in accordance with the general arrangement of the stove, these valves may be located otherwise than as shown, that is, they may be assembled close to one another on the same side of the stove, if desired. Following the closing of the air, gas and chimney valves, the cold blast valve 33 is opened and when the pressure in the stove becomes equal to that in the hot blast outlet main, the hot blast valve 25 is opened and the cold air then passes by means, first, of the chimney flue 30, through the stove in a direction opposite to that path of the products of combustion taken in heating the stove.

lVhen the temperature of the masonry falls below that required to heat the blast to the desired temperature, the process is repeated.

It will be seen that the above four pass stove obtains the results of providing a down draft of the products of combustion through the checker-work and permits of a larger regenerative surface in the masonry without excessive height of the stove as is now necessary in both the two pass and three ass stoves. Not only is there an advanta e p c 1-,

in increasing the width of the stove in reference to the height, due to the dangerous stress imposed on the masonry at the bottom, and also in that the regenerative surface increases directly in proportion to the height as the square of the diameter.

It will also be noted that the passes are entirely separated, thereby allowing for an independent contraction and expansion and the provision of the slip joint construction. It is also very important in hot blast stoves of all kinds to have a uniform temperature throughout any pass at any given level, and in the construction illustrated, this is accomplished by passing the products of combustion downward through all the checkerwork and interposing between the inner and outer checker-work means for allowing a rapid passage of the gases from the bottom of the lower inner checker-work to the top of the outer checker-work, and the flues constituting such connecting means for the said checker-works are of such size that they will permit the passage of the products of combustion without undue friction, but no larger. It should be noted that if these flues are made too large, they will cause back draft in some of the flues.

What I claim is Y 1 1. A hot blast stove having a central combustion chamber constituting the first pass, a plurality of concentric passes outside of the first pass, said passes alternately com municating at top and bottom, cold blast ad mission and combustion products. outlet means at the bottom of the stove, and oneof said passes being formed of a series of separate flues, the total area of which is substant-ially equal to the area of the said outlet. 7 V r 2. A hot blast stove having a central or first pass, an annular second pass, an annular wall surrounding the second pass and having flues embedded therein constituting the thlrd passyand an annular fourth pass surrounding the said wall, said embedded flues forming the communication between the sec- 0nd and fourth passes.

3. A hot blast stove having a central or first pass, an annular second pass, an annular wall surrounding the second pass and having a series of independent spaced-apart flues embedded therein constituting the third pass, and an annular fourth pass surrounding said wall, said flues forming communication between the second and fourth passes.

A. A hot blast stove having a central or first ass, an annular second pass, an annular wall surrounding the second pass and having flues embedded therein constituting the third pass, an annular chamber adjacent the lower end of the second pass, and an annular fourth pass surrounding said wall, said embedded flues in open communication with the annular chamber and formlng communr. catlon between the second and fourth passes.

5. A hot blast stove having a central combustion chamber .cOl1Sl3itHt-lng a pass for the.

6. A hot blast stove having a central com-' bustion chamber forming a first pass, an annular concentric second pass surrounding the chamber, and provided. with checkerwork having relatively large fiuespaces, a third annular outer pass formed of continuous independent separate flues forming communication between the second and fourth passes, and a fourth outer pass having checker-work of smaller flue space thanthe I second pass. I

7. A four passhot blast stove having a central or first pass free of checkerwork,

an annular second pass having checker- Work therein, an annular Wall surrounding In testimony whereof I aflix my signature the second pass having independent fines in presence of two Witnesses. embedded therein, and an annular fourth WVALTER O. AMSLER. pass having eheokerwork therein, said 6111- Witnesses:

5 bedded fiues forming communication be- W. G. DOOLITTLE, tween the second and fourth passes. ALICE B. DICE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

